This invention relates to equipment and methods for the removal of crud formed at the interface between aqueous and organic phases in solvent extraction processes for the recovery of metal from metal ores.
A major problem in solvent extraction plants used for the solvent extraction of metal values from aqueous solutions obtained from the leaching of metal ores is the formation of interfacial sludge, commonly referred to as gunk or crud. Excess crud formation can lead to a number of problems, requiring the regular removal of the crud from the settling tanks. Known methods for the removal of crud are almost all labor intensive, i. e. involve the physical removal of the crud by an operator.
Since the crud is at least about 50% organic, it is economically important to recover most if not all of the entrained organic phase.
The present invention relates to novel methods and equipment that function effectively to remove the crud without the need for constant operator monitoring.
The process of the invention is carried out by means of at least one rotating auger (conveyor screw) positioned at the interface between the aqueous and organic phases in an SX settler used in the solvent extraction process for recovering metal from metal ores, e.g. copper ores, nickel ores, zinc ores, uranium ores, etc. The rotating auger(s) are run continuously or intermittently at timed intervals to remove crud from the liquids interface. The SX settlers are sometimes referred to as mixer-settlers.